Angular scattering of low-energy electrons by atomic and molecular oxygen, argon, and helium

Abstract

The differential cross sections for electrons scattered by He, O, Ar, and ${\mathrm{O}}_2$ at 15 eV and by O and ${\mathrm{O}}_2$ at 5 eV have been determined using a modulated crossed-beam technique. The results for He, Ar and ${\mathrm{O}}_2$ agree well with previously published experimental and theoretical values. Measurements on ${\mathrm{O}}_2$ extend to larger back-scattered angles than previously reported. Results for O are compared with the theoretical calculations of Thomas and Nesbet. Reasonable agreement with theory is obtained at 5 eV, and while the calculations only extend to 11.0 eV, the trend in shape appears correct at 15 eV. A small-angle dip in the cross section is observed which is not predicted by the theory.